Panel lift clamp assembly

ABSTRACT

The specification and drawings disclose a clamp assembly particularly suited for handling large construction panels, prefabricated wall sections, and the like. The structure comprises an elongated frame having a pivoted lift member connected generally at the center of one side. Extending from the opposite side of the frame are a plurality of opposed pairs of clamp plates. The clamp plates in each pair are arranged for adjusting movement toward and away from one another. Additionally, biasing means are provided to permit each plate to tilt to compensate for irregularities in a panel being clamped and lifted. Also, the biasing means function to return the clamp plates to their original position after they are disengaged from the panel.

United States Patent Taylor [451 July 25,1972

[54] PANEL LIFT CLAMP ASSEMBLY [72] Inventor: Robert B. Taylor, NorthCanton, Ohio [73] Assignee: Metropolitan industries, Inc., Canton,

Ohio

[22] Filed: Feb. 12, 1971 [2]] Appl.No.: 114,762

Primary Examiner-Evon C. Blunk Assistant Examiner-l. Kenneth SiivermanAttorney-Fay, Sharpe & Muiholland [57] ABSTRACT The specification anddrawings disclose a clamp assembly particularly suited for handlinglarge construction panels, prefabricated wall sections, and the like.The structure comprises an elongated frame having a pivoted lift memberconnected generally at the center of one side. Extending from theopposite side of the frame are a plurality of opposed pairs of clampplates. The clamp plates in each pair are arranged for adjustingmovement toward and away from one another. Additionally, biasing meansare provided to permit each plate to tilt to compensate forirregularities in a panel being clamped and lifted. Also, the biasingmeans function to return the clamp plates to their original positionafter they are disengaged from the panel.

13 Claims, 7 Drawing Figures mzmtnm m2 3.679.254

sum 2 or 5 INVENTOR. 05527 5. MVLOQ 7%, 3% mama PANEL LIFT CLAMPASSEMBLY BACKGROUND OF THE INVENTION The subject invention is directedtoward the material handling art and, more particularly, to an improvedclamp assembly for handling large rectangular members.

The invention is particularly suited for handling prefabricated buildingpanels such as wall and partition sections and will be described withparticular reference thereto; however, as will become apparent, theinvention is capable of broader application and could be used forhandling many types of panels, sheet materials and the like.

In recent years, it has become increasingly common to prefabricate largebuilding sections such as interior and exterior walls, and other largebuilding panels in a factory or shop and transport them to the job sitewhere they are installed. It has been found that this substantiallyreduces construction costs and speeds the construction process.

One of the problems with the prefabricated type of construction has beenthe difficulty of handling the large panels without damaging them. Inmany instances, their size is such that they must be lifted and movedinto position by some type of power operated lifting mechanism such as acrane. Difficulties are encountered in connecting the lifting cables tothe panels without causing damage to the panels. In some instances,lifting lugs and the like are built directly into the panels.Additionally, lugs, cavities, etc., usually require more expensive formwork and increased steel reinforcing. This merely increases the cost ofthe panels and, in many instances, increases the labor involved sinceremoval of the panel lift lugs must often be done after the panels areinstalled.

GENERAL DESCRIPTION OF THE INVENTION The present invention overcomes theabove problems and provides a lift clamp assembly which can be used forpositively gripping the panels and providing means for connection of thenecessary lifting cables and the like. The clamp assembly is designed sothat it compensates for any minor thickness variations, uneveness in thepanel, or the like. Further, the inventive clamp structure is arrangedso that it quickly adjusts to varying panel thicknesses andconfigurations.

In accordance with the invention, there is provided a lift clampassembly particularly suited for handling large structural panels or thelike comprising an elongated frame carrying at least a pair of clampplate members having generally aligned and opposed clamping surfaces.Adjusting means are provided for selectively moving the clamping surfaceof at least one of the clamp plate members toward and away from theclamping surface of the other to grip opposed surfaces of a bodypositioned therebetween. Connected to the clamp plate members arebiasing means which function to permit relative tilting movement betweenthe clamping surfaces to compensate for any non-parallelism of theopposed surfaces gripped on the body and to return the gripping surfaceto approximate parallelism after engagement with the body.

Because of the arrangement of the clamp plates of the biasing means, theclamping surfaces can tilt or shift to mate with the panel surfaceswhich are not perfectly flat or parallel. Additionally, after the clampassembly is disengaged from a panel, the clamp members automaticallyreturn to their original, generally parallel relationship for readyengagement with another panel.

In accordance with another aspect of the invention, it is contemplatedthat a plurality of pairs of clamp members will be carried on a singleelongated frame and that a lift member will be pivotally connected tothe frame generally at its midpoint. This arrangement permits the clampassembly to be clamped to a vertical edge of a panel and the lift memberpivoted to extend in a direction most convenient for attachment to alift hook or the like.

Accordingly, a primary object of the invention is the provision of apanel lift clamp assembly which includes adjustable lifting plates orpads that can individually shift to compensate BRIEF DESCRIPTION OF THEDRAWINGS The above and other objects and advantages will become apparentfrom the following description when read in conjunction with theaccompanying drawings wherein:

FIG. 1 is a side elevation of a lift clamp assembly formed in accordancewith the preferred embodiment of the invention;

FIG. 2 is an elevational view showing the side of the lift clampassembly opposite from that shown in FIG. 1;

FIG. 3 is a bottom view taken on line 3-3 of FIG. 1;

FIG. 4 is an end elevation taken on line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 2 and showingdetails of one of the clamp plate assemblies;

FIG. 6 is an elevational view showing the lift clamp assembly being usedfor removing a construction panel from the bed of a truck; and

FIG. 7 is an elevational view showing the lift clamp assembly being usedfor raising a construction panel.

DETAILED DESCRIPTION OF THE DRAWINGS opposed cooperating pairs along thelength of the frame assembly l0.

FRAME ASSEMBLY 10 The frame assembly could take many forms and have avariety of different constructions; however, according to the preferredembodiment, the frame comprises a first elongated channel member 16which, as best shown in FIG. 4, is positioned with its flanges 18extending vertically upwardly. Connected to the flanges l8 and extendingdownwardly therefrom are somewhat shorter channel sections 20 and 22.The channel sections 20 and 22 are positioned in opposed pairs and areconnected to the horizontal channel 18 in any convenient manner such asby welding. Reinforcing plates 24 are joined across the upper ends ofeach opposed pair of channels 20, 22. This provides a rigid, elongatedframe having a generally inverted U-shape when viewed from the end.

In order to facilitate handling and lifting, a lift hook assembly 26 isconnected to the frame. Many different types of lift assemblies could beprovided and connected to the main frame 10 at different points;however, according to the preferred embodiment, the lift hook assembly26 is preferably connected to frame 10 on the line passing verticallythrough the assemblys center of gravity. Additionally, the hook assemblyis arranged so that it can pivot relative to the frame assembly 10. Inother words, the frame 10 is self-locating relative to the lift hookassembly and torque cannot be applied from the frame to the upper end ofthe lift assembly.

The preferred structural details of the hook assembly 26 are best shownin FIGS. 1 and 4. Specifically, the hook assembly comprises a liftmember 28 formed from pipes or rod and having a tapered U-shape shown inFIG. 4. A pair of transversely extending rods or bars 30 are connectedbetween the legs of member 28 for structural stability. The lower end ofeach of the legs is provided with sleeves or bearing members 32 whichreceive a center shaft or pivot shaft 34. It should be understood thatthe sleeves 32 are freely rotatable relative to the shaft 34.

The shaft 34 is positively connected to the frame assembly by beingwelded to the center reinforcing plate 24.

CLAMP PLATE ASSEMBLIES 12 and 14 In the embodiment under consideration,there are three sets of clamp plate assemblies 12 and 14 locatedsymmetrically relative to the channel 18. As will become apparent, agreater or lesser number of pairs of these clamp assemblies could beutilized without departing from the invention. Additionally, althougheach of the pairs of clamp assemblies is identical, it should, ofcourse, be understood that the details of construction of theseassemblies could vary from that shown and individual pairs could be madeslightly different than other pairs.

In the embodiment shown, since each pair is identical, only one pairwill be described in detail. Like reference numerals will be utilized toidentify corresponding parts in each pair and a description of one suchpart is to be taken as equally applicable to the others unless otherwisenoted.

Specifically, the clamp plate assembly 12 comprises a first rectangularmetal clamp plate 38 having a removable member 40 carried thereon anddefining the clamping surface. The clamping surface defining member 40is formed from any suitable material such as heavy plastic, masonite,rubber sheeting or the like and is joined or otherwise connected to theplate 38 in any convenient manner. In the embodiment underconsideration, plate 40 is connected to plate 38 by a plurality of flathead machine bolts 42 which have their heads received in counter-sunkrecesses formed inwardly of the outer surface. This arrangement providesa flat clamping surface which engages the panels or wall sections whichare to be lifted.

Of particular importance to the invention is the mounting of the clampplate 38 to allow it to have a freedom of movement in 2 about its centerpoint. This allows the clamping surface to adjust to irregular panelsurfaces without causing undue stress on any one point. Many differenttypes of mountings could be used; however, in the subject embodiment,the mounting comprises four stud bolt or shaft members 44 which arewelded to the back side of plate 38 and extend perpendicularly therefrom(see FIGS. 1, 3 and 4). The stud bolt members 44 are uniformly locatedrelative to the center of plate 38. As best shown in FIGS. 1 and 3, thestuds pass through plates or support bars 46 welded to the verticallyextending channels 20. Openings are formed through the support bars 46of sufficient large size so that the studs pass freely therethrough toallow tilting of the plate relative to the support bars.

The studs are maintained under a continual bias acting to draw the clampplate 36 toward the channels 20. The biasing means comprise coil springs48 positioned about the outer end of each stud 44 and acting between theback surface of the support bars 46 and a washer 50 held on the studs bysuitable nuts 52.

In order to permit adjustment of the clamp plate 38 and move itoutwardly from the channel against the bias of the coil springs 48, athreaded adjusting member is positioned to engage generally at thecenter of plate 38. In the embodiment under consideration, the threadedadjusting member comprises a threaded rod 60 having a handle 62 carriedat its outer end. Its inner end portion is threaded as shown at 64 andpasses through a nut 66 tack-welded to the back surface of the web ofchannel 20. The innermost end 68 of shaft 64 is rounded slightly andengages the center of plate 38. A washer or annular locating member 70is joined to plate 38 and surrounds the end of shaft 60.

The arrangement thus far described allows adjustment of the lateralposition of plate 38 while permitting it to tilt or pivot somewhat aboutthe stud end 68. Since the studs 44 are symmetrically located relativeto the end 68, the springs 48 provide a centering action on the clampplate 38. That is, when the plate is not in engagement with'a panel orother member being lifted, it automatically assumes a positionperpendicular to shaft 60.

As previously mentioned, each of the clamp plate assemblies 12cooperates with a corresponding one of the clamp plate assemblies 14. Asbest shown in FIGS. 2 and 3, each clamp plate assembly 14 comprises arectangular metal clamp plate member 76 having a sheet or plate ofmaterial 78 connected to its inner face and defining the clampingsurface. The material 78 is preferably releasably connected to the plate76 by a plurality of flat head machine bolts 80 (see FIG. 5) which havetheir heads received in recessed openings 82 formed in the sheetmaterial 78.

The clamp plates 76 are mounted so as to allow limited tilting abouttheir center points so that they can readily align with the panel beinglifted or the opposed clamp plate 38. For this reason, a stud member 84is welded to the center of the rear surface of plate 76 and extendsthrough a somewhat larger diameter opening formed in the web of thedownwardly extending channel 22. The opening through which the studextends is, of course, sufficiently large to permit substantial tiltingof the plate 76 relative to the channel 22. Additionally, ahemispherical washer or pivot member 86 is positioned about the innerend of stud 84 to provide a pivotal surface for engaging the face of theweb of channel 22. The hemispherical member 86 is biased into engagementwith the web by a coil spring 88 which surrounds the outer end of stud84 and is compressed between the web of the channel and a washer 90 heldon shaft or stud 84 by a nut 92. As can be appreciated, this arrangementprovides for tilting and shifting adjustment of the clamping surface ofassembly 14.

In order to assure that the clamp plates 76 return to proper alignmentafter disengagement from a panel member, the three clamp plates 76 areresiliently interconnected and biased in the manner best shown in FIGS.2 and 3. Note that coil springs 94 are connected between adjacent clampplates 76. The coil springs 94 are connected to the plates under tensionwith a pair of the springs located between each adjacent pair of clampplates 76. The locations of the connections for the coil springs areequidistant from the horizontal and vertical center lines through thecenter of the individual clamp plates. Consequently, after the clampassemblies have been released, the springs 94 act to return the platesthe horizontal and vertical alignment. This is because the springs movethe plate to equalize the force or tension being applied by each andthus return the plates to their original positions.

While it is apparent from the drawings and the above description, itshould be stated clearly, the combination of springs 48, 88 and 94 acttogether to maintain the mouth of the clamp in wide open to facilitateeasy insertion of a panel. The automatic self-aligning features speedthe operation considerably.

Referring to FIGS. 6 and 7, the use of the clamp panel lifting assemblyto perform one type of lifting operation is illustrated. Note that awall panel or the like is shown lying in a horizontal position on theback of a truck 102 shown in phantom lines. The lift clamp assembly is,in this instance, connected to the vertical end edge of the panel 100since the panel is to be moved to stand at a ninety degree relationshipfrom the position in which it is delivered. In connecting the clampassembly, the assembly is opened to a width sufficient to freely passonto the panel and, thereafter, the handles 62 are manually rotated totighten the clamp plates 38 into en gagement with the one surface of thepanel and draw the clamp plates 76 into engagement with the oppositesurface. The previously mentioned centering arrangements allow the clampplates to adjust to any slight irregularities or non-parallelism of thesurfaces of the panel and prevent undue forces from being applied at anypoint on the panel. With the clamp assembly firmly attached to the endof the panel, the lift hook assembly is pivoted to a position where itcan be readily connected to the lifting cables or hooks (a lift hook 104is shown carried on the end of a crane 106). Although not previouslymentioned, the length of the lift hook assembly is preferably longenough so that it extends beyond the outer end of the frame 10 so thatconnection can be made without damage to the panel. After the lift hookhas been properly connected, a

vertical lift of the hook causes the panel to be pivoted about and moveto a vertically extending position as shown in FIG. 7.

The invention has been described in great detail sufficient to enableone of ordinary skill in the clamp art to make and use the same.Obviously, modifications and alterations of the preferred embodimentwill occur upon a reading and understanding of the specification and itis my intention to include all such modifications and alterations aspart of my invention insofar as they come within the scope of theappended claims.

What is claimed is:

l. A lift clamp assembly for use in handling large panels or the likebodies comprising:

a. an elongated frame;

b. at least two pairs of clamp plate members depending from said frameand having generally aligned and opposed clamping surfaces;

c. adjusting means for selectively moving the clamping surface of atleast one of said clamp plate members toward and away from the clampingsurface of the other to grip opposed surfaces of a body positionedtherebetween; and,

d. biasing means connected to each of said clamp plate members forpermitting relative movement between said clamping surfaces tocompensate for non-parallelism of the opposed surfaces gripped on thebody and to return said gripping surfaces to approximate parallelismafter disengagement from the body, said biasing means including springsconnected between adjacent clamp plates.

2. The lift clamp assembly defined in claim 1 wherein said adjustingmeans comprise a threaded member positioned to engage one of said clampplate members on the side opposite its clamping surface and wherein saidbiasing means include a plurality of springs located about said threadedmember.

3. The lift clamp assembly as defined in claim 1 including a lift memberconnected to said frame at a location generally intermediate said liftplates.

4. The lift clamp assembly as defined in claim 1 wherein said clampassemblies are each independently adjustable and wherein said biasingmeans further include springs located uniformly about said adjustingmeans.

5. The lift clamp assembly as defined in claim 1 including a lift memberconnected to said frame, said lift member being pivotally connected tosaid frame generally at the center thereof.

6. The lift clamp assembly as defined in claim 5 wherein said liftmember has a length greater than one-half the length of said frame.

7. A lift clamp assembly including: a frame carrying at least a pair ofopposed first and second clamp plate members having aligned clampingsurfaces;

adjusting means for varying the spacing between said clamping surfacesand including a movable member engaging the first clamp plate on theside opposite its clamping surface;

first biasing means biasing said first clamp member into engagement withsaid movable member for maintaining said plate in engagement therewithwhile permitting it to tilt relative thereto; and,

said second plate member being pivotally connected to said frame andsecond biasing means for maintaining said second plate member biasedtoward said frame while permitting tilting relative to said frame,

said second clamp plate being connected to said frame by a stud memberwhich extends through said frame, said stud member carrying ahemispherical surface which engages said frame; and, wherein said secondbiasing means includes means for maintaining said hemispherical surfacebiased into engagement with said frame.

8. The lift clamp assembly as defined in claim 7 wherein said firstbiasing means comprise a plurality of springs positioned about saidmovable member.

9. The lift clamp assembly defined in claim 8 including at least twopairs of said clamp plate members carried at longitudinallyTslpacedpoints on said frame.

10. e lift clamp assembly of claim 7 including a second pair of saidfirst and second clamp plate members carried by said frame at locationsspaced from said first pair.

11. The lift clamp assembly as defined in claim 10 wherein said secondbiasing means include springs interconnecting the second clamp plates ofeach pair.

12. The lift clamp assembly as defined in claim 7 wherein said clampassemblies are each independently adjustable and wherein said biasingmeans further include springs located uniformly about said adjustingmeans.

13. The lift clamp assembly as defined in claim 9 including a liftmember connected to said frame, said lift member being pivotallyconnected to said frame generally at the center thereof.

1. A lift clamp assembly for use in handling large panels or the likebodies comprising: a. an elongated frame; b. at least two pairs of clampplate members depending from said frame and having generally aligned andopposed clamping surfaces; c. adjusting means for selectively moving theclamping surface of at least one of said clamp plate members toward andaway from the clamping surface of the other to grip opposed surfaces ofa body positioned therebetween; and, d. biasing means connected to eachof said clamp plate members for permitting relative movement betweensaid clamping surfaces to compensate for non-parallelism of the opposedsurfaces gripped on the body and to return said gripping surfaces toapproximate parallelism after disengagement from the body, said biasingmeans including springs connected between adjacent clamp plates.
 2. Thelift clamp assembly defined in claim 1 wherein said adjusting meanscomprise a threaded member positioned to engage one of said clamp platemembers on the side opposite its clamping surface and wherein saidbiasing means include a plurality of springs located about said threadedmember.
 3. The lift clamp assembly as defined in claim 1 including alift member connected to said frame at a location generally intermediatesaid lift plates.
 4. The lift clamp assembly as defined in claim 1wherein said clamp assemblies are each independently adjustable andwherein said biasing means further include springs located uniformlyabout said adjusting means.
 5. The lift clamp assembly as defined inclaim 1 including a lift member connected to said frame, said liftmember being pivotally connected to said frame generally at the centerthereof.
 6. The lift clamp assembly as definEd in claim 5 wherein saidlift member has a length greater than one-half the length of said frame.7. A lift clamp assembly including: a frame carrying at least a pair ofopposed first and second clamp plate members having aligned clampingsurfaces; adjusting means for varying the spacing between said clampingsurfaces and including a movable member engaging the first clamp plateon the side opposite its clamping surface; first biasing means biasingsaid first clamp member into engagement with said movable member formaintaining said plate in engagement therewith while permitting it totilt relative thereto; and, said second plate member being pivotallyconnected to said frame and second biasing means for maintaining saidsecond plate member biased toward said frame while permitting tiltingrelative to said frame, said second clamp plate being connected to saidframe by a stud member which extends through said frame, said studmember carrying a hemispherical surface which engages said frame; and,wherein said second biasing means includes means for maintaining saidhemispherical surface biased into engagement with said frame.
 8. Thelift clamp assembly as defined in claim 7 wherein said first biasingmeans comprise a plurality of springs positioned about said movablemember.
 9. The lift clamp assembly defined in claim 8 including at leasttwo pairs of said clamp plate members carried at longitudinally spacedpoints on said frame.
 10. The lift clamp assembly of claim 7 including asecond pair of said first and second clamp plate members carried by saidframe at locations spaced from said first pair.
 11. The lift clampassembly as defined in claim 10 wherein said second biasing meansinclude springs interconnecting the second clamp plates of each pair.12. The lift clamp assembly as defined in claim 7 wherein said clampassemblies are each independently adjustable and wherein said biasingmeans further include springs located uniformly about said adjustingmeans.
 13. The lift clamp assembly as defined in claim 9 including alift member connected to said frame, said lift member being pivotallyconnected to said frame generally at the center thereof.